GCSE's then A Levels then Uni to study Physics and Instrumentation... then started work as a Marketing Assistant.
Quite enjoyed it so completed a Diploma in Marketing qualification and moved jobs increasing salary for a few years... then got bored, retrained doing an MCSE (Microsoft Certified Systems Engineer) and moved into IT back at the same College I started in as the Marketing Assistant!
Worked for nearly a year doing IT Service Desk stuff then promoted into different team to do Web Development.
So, still in IT but in different branch doing way more interesting stuff. Along the way I have passed various courses which may well help if I ever move onwards (ITIL Foundation certificate, PRINCE II Foundation & Practitioner etc. etc.) and I *still* have no real idea of what I want to do.
I do my job, it's reasonably enjoyable, it pays the bills and allows me time to spend with my family.... if I get bored then I suspect I'll just retrain and move on again.
Lifelong Learning.
Basically don't think that your decision now is the one you are stuck with for the rest of your life. It's never too late to change/retrain and move on. Fresh challenge, new people etc. It's all good!!!